If you've been making home improvements to increase the energy efficiency of your house, you may be overlooking a key ingredient. Re-doing windows and replacing light bulbs are all well and good, but you may be forgetting one of the largest 'rooms' in your home: your garage. Especially if you live in a place that has cold winters and hot summers, you are likely wasting a lot of energy keeping your garage at an even temperature as the heat seeps in and out through your unprotected door. Even if you don't, the afternoon sun can really beat down on the garage door and heat it up.
There are many different products you can buy to insulate your garage door. "Reflectix Insulation" is just one of these. Most come in rolls and are some sort of soil with bubble or other space-inhabiting substance in between the two layers of foil. You just cut the pieces to fit the door size and install them according to the instructions on the package. The work itself takes less than an hour.
Such a simple step, but it can really cut down on the heat/cold in your garage, so you don't waste energy trying to maintain an even temperature.